Interim results for Vertu Motors show pre-tax profits rose 48.8% year-on-year to £12.8m in the six months to August 31.
Half year revenues were up by £246.7m to £1.08 billion, a 29.5% rise.
Growth was fuelled by acquisitions of six further sales outlets since March. However Vertu reported that like for like retail new vehicle sales volume was up 11.8%, fleet cars rose 12.4%, commercial vehicles rose 28.6% and used vehicle volumes were up 11.6%.
Overall group margin suffered a drop to 10.6% from 11.1% due to a higher proportion of vehicle sales and the continued manufacturer push of new vehicle supply into the UK.
Chief executive Robert Forrester said: "The board is delighted with this record first half performance. Recent acquisitions, the Farnell Land Rover business particularly, have made a strong contribution and the core business continues to benefit from management success in improving returns in the used car and servicing areas.
"We continue to deliver on the group's strategy to recruit and retain motivated and talented people in every dealership to ensure the business is management driven not market driven."
Vertu expects full year results to be in line with market expectations, and said it experienced a strong trading performance in September with a 8.3% rise in like for like new retail volume and 8.6% higher service revenues.
The filing to the stock exchange reveals Vertu has closed its final Motor Nation used car supermarket in Birmingham, allowing the group to concentrate on its core activity of operating franchised dealerships. That site is now being used for fleet vehicle storage.